I've never seen it done, or known anyone personally that has done it, but a few years ago I was sitting on about a half O headstash that lasted me an incredibly long time, I built up no tolerance, and it was most definitely the most potent extract I have ever consumed. I know it was made in the PNW, and it was called 'sugar hash,' but referred to as 'sugs' (pronounced shugz) by those lucky enough to procure some. I was not all that close to the source, and it was before I really knew anything about cannabis/resin science. I do know that it was made from multiple strains, and it was incredible. I have seen others comment on similar posts as mine, saying things like, "it was probably just BHO with dry sift mixed in." Well I know for a fact it was not, as I have smoked BHO since then and was not a fan, regardless of whether or not it was mixed with anything. I know there are some posters who have had the exact same thing as me, for their descriptions have been identical to how I would describe it: Brown Sugar that is slightly moist. Very granular in texture, i.e. the carboxylated ring has not been rupture, and the resin heads are entirely intact. If one has the equipment/ knowhow, it seems to be the best choice for extraction, IMO. Zero contaminants, no water soluble terps washed away, comparable yield (I presume) to BHO, without the potential long term repercussions.
(I do not mean to start a BHO war here, I am simply stating the obvious that this process has not been done for long enough, consumed long enough, nor has it been studied long enough to know for sure if it is harmful. I like to walk on this side of caution when it comes to what I put in my body, especially if I am smoking/vaping it. Most of you probably know that DDT used to be sprayed on residential neighborhoods, crowds of people while having picnics, soldiers, etc. My dad tells stories of when his doctor would tell him to have a cigarette, in order to calm his nerves. Cops pulling him and his friends over, each one with a beer in his hand and case a beer in the car. "Have a good night, boys." The point is what is deemed safe today may not be in 20 years. Who knows, maybe you are all completely right, and the butane is "purged," I am not trying to argue whether it is true or not, simply that there is not enough information to deem it true or false, just questionable.)
"The door to novelty is always slightly ajar: many pass it by with barely a glance, some peek inside but choose not to enter, others dash in and dash out again; while a few, drawn by curiosity, boredom, rebellion, or circumstance, venture in so deep or wander in there so long that the can never find their way back out."